Photovoltaic-thermoelectric Hybrid Research Articles

Investigating the power and efficiency of the 3D model of the concentrated photovoltaic thermoelectric hybrid system and estimating the power consumption of the water pump for cooling

Solar energy is one of the most useful types of renewable energy. Solar cells are being used to convert solar energy into electricity. By focusing the radiation on the cells, more energy is radiated in a smaller area of the cell which is called concentrated photovoltaic (CPV). Due to the concentration of radiation, the temperature of the cell rises which can be converted into electricity through thermoelectric generators (TEG). The present study is a hybrid system of solar cell, thermoelectric generator, and heat exchanger (CPV-TEG). By this survey being created, it was revealed that the combined power produced by the CPV-TEG reaches its maximum value at concentration ratio of 40. This increase continues with the increase in fluid flow rate. however, according to the power consumption of the pump, it was observed that in all types of heat exchangers, an increase in flow rate of more than 8 liters per hour reduces the output power of the system. The replacement of the secondary heat exchanger with the primary one illustrated that the increase of the channels in the exchanger, despite the increase in the power consumption of the pump, causes a very small increase in the output power and efficiency of the system. Moreover, replacing the tertiary heat exchanger instead of the secondary exchanger showed that changing the direction of fluid output increases the power consumption of the pump in high flow rates.

Multiphysics modeling tool for photovoltaic-thermoelectric hybrid devices integrating a photothermal interface

Photovoltaic-thermoelectric hybrid devices aim at harvesting the entire solar spectrum via both direct photovoltaic conversion and subsequent thermoelectric conversion of the heat generated in the solar cell. One emerging strategy to improve their efficiency is to implement a photothermal interface between the photovoltaic cell and the thermoelectric module. Modeling such a complex system (photovoltaic cell, photothermal interface and thermoelectric generator) to design an optimal architecture is a challenging task, as it requires to take into account a large number of parameters in a multi-layered system, as well as the coupling between optical, thermal and electrical effects. To do so, we present here a multiphysics tool to predict the temperature distribution and power output of hybrid devices integrating a photothermal interface. Our model shows a good quantitative agreement with previous theoretical and experimental works from the literature using limited material parameters. We discuss the need for additional parameters for accurate modeling of experimental devices. We envision that our multiphysics modeling tool will be key for the design of optimal photothermal interfaces for efficient photovoltaic-thermoelectric hybrid devices.

Experimental optimization of a spectrum-splitting photovoltaic-thermoelectric hybrid system

This paper provides a comprehensive experimental optimization of a spectrum-splitting photovoltaic-thermoelectric hybrid system. A steady-state experimental setup is established. The properties of the coupling system with different splitter cutoff wavelengths and thermoelectric device structures are tested and compared with the single photovoltaic system under the same conditions. The effects of concentration ratio, cooling water temperature, and flow rate on the coupling properties are also experimentally investigated. The results show that among the three cutoff wavelengths tested, 880 nm, 990 nm, and 1100 nm, the coupling system using the 880 nm cutoff wavelength splitter performs best with the highest output power of 1.64 W. The coupling utilization can boost the power by 49.1 % compared to the 1.1 W power of the single photovoltaic system. Effective enhancement in the coupling property can be achieved by increasing the thermoelectric leg height, elevating the concentration ratio, lowering the cooling water temperature, and enhancing the flow rate. The coupling system output power is increased by 24.2 % by raising the thermoelectric leg height from 1.0 mm to 1.5 mm. When increasing the concentration ratio from 55 to 146, the total system power improves by 65 %, and the thermoelectric power ratio of the total power rises from 15.2 % to 37.5 %. The results can be used to guide the subsequent studies and practical applications of the spectrum-splitting photovoltaic-thermoelectric hybrid system.

Optimization of the performance and operation of a photovoltaic-thermoelectric power supply system for bridge safety monitoring microsystems

In the long-term unattended condition, the continuous operation of bridge safety monitoring micro-system (BSMMS) in mountain areas has the issue of insufficient energy supply. Therefore, a photovoltaic-thermoelectric hybrid power generation system (PV-TEG) is proposed to power the temperature, wind speed, and tilt sensors of BSMMS. The power generation performance and characteristics of PV and TEG are experimentally investigated to find the operation mode to match the bridge monitoring. In addition, the intermittent operation mode of BSMMS is optimized to achieve longer running times. The experimental results show that the output voltage and power generation of the PV-TEG can meet the energy consumption demands of all sensors. TEG power generation is linear with bridge temperature, which can trigger TEG to support the temperature sensor operation. The energy storage battery supports the BSMMS to run for 8.99 days in the mode of running 5 min every 5-min intervals. Optimizing the operation time and interval of the BSMMS to run once in half an hour, it can run continuously for up to 17.97–22.46 days. This work provides a reference for the design of an unattended self-powered energy supply system for a multi-parameter integrated bridge safety monitoring system.

Feasibility study on radioisotope-powered thermophotovoltaic/thermoelectric hybrid power generation system used in deep-sea: From design to experiment

This study aims to comprehensively examine the feasibility of a hybrid power generation system that integrates solar and thermoelectric technologies, with a focus on utilizing a radioisotope heat source (RHU) for deep-sea applications. The investigation encompasses the whole design process as well as rigorous testing procedures. The self-designed coupling device establishes a connection between the silicon photovoltaic (PV) cell and the bismuth telluride (Bi2Te3) thermoelectric modules (TEMs), therefore creating a photovoltaic-thermoelectric (PV-TE) hybrid system. The measuring platform incorporates the system to investigate the influence of varying light intensity (ranging from 400 to 1600 W/m2) on the electrical properties of the system, specifically focusing on three subgroups of PV cell temperature (20 °C, 25 °C, and 30 °C). The findings suggest that the enhanced performance of the photovoltaic (PV) cell and thermoelectric modules (TEMs) under identical PV cell temperatures may lead to an improvement in the electrical performance of the system due to variations in light intensity. Nevertheless, when the temperature of the photovoltaic (PV) cell increases, there is a gradual decline in the growth rate of the output power. The subsequent research provide evidence that there exist discrete mechanisms responsible for the reduction in intensity between thermoelectric modules (TEMs) and photovoltaic (PV) cells. The processes arise due to the impact of thermal effect on the photovoltaic materials and the increased temperature difference between hot and cold junctions of the thermoelectric modules (TEMs), respectively. Furthermore, a control group is incorporated by calculating the performance of the hybrid system under the same operating conditions as the single thermoelectric (S-TE) system. According to a comparative analysis comparing the Radioisotope Thermal-Photovoltaic-Thermoelectric (RTPV-TE) hybrid power production systems and the S-TE system, it has been shown that the former exhibits a potential increase in output power of up to 271% while operating under identical conditions. This work offers insights and methodologies for the design and measurement of RTPV-TE hybrid power generating systems in engineering application situations.

Self-Adaptive PDLC Control Strategy With Smart Light Intensity Adjustment Using Photovoltaic-Thermoelectric Hybrid Energy Supply Technology

As an electronically controlled glass whose transmittance varies with voltage, polymer dispersed liquid crystal (PDLC) has the advantages of good privacy, high transmittance, fast response speed, and good heat shielding performance. It can be applied to electronically controlled building windows. However, PDLC needs to consume extra power, and electronically controlled PDLC has not yet been integrated with intelligent home environment control. In this paper, we proposed an adaptive variable voltage step-size fast control algorithm in Field Programmable Gate Array (FPGA)-based home environment control system, which is powered by photovoltaic-thermoelectric (PV-TEG) hybrid sources. The power supply voltage of the PDLC can be dynamically changed through the adaptive Pulse width modulation (PWM) duty cycle adjustment technology to realize intelligent transmittance control, thereby improving the indoor lighting environment. Experimental results show that by applying the proposed algorithm, the indoor temperature is reduced by 2°C, and the adaptive and stable regulation of the optimal indoor illumination of 500 Lux can be completed in less than 2.5 seconds. This paper provides a feasible solution for the low-energy intelligent integrated control and monitoring of the modern home environment.

Performance analysis and structure optimization for concentrated photovoltaic-phase change material-thermoelectric system in space conditions

High-efficient thermal management is urgently needed for concentrated photovoltaic-thermoelectric hybrid system due to the high heat flux. In present paper, a three-dimensional model for the hybrid system in outer space conditions was established by coupling phase change temperature control and radiation heat sink technologies to find the propriate thermal management scheme. Firstly, the three shortcomings in the typical hybrid system were proposed and their adverse effects on efficiency were elucidated. Then, a heat transfer pillar for temperature control unit and a newly designed circular fins for heat sink were designed. The effects of structure parameters on power generation performance were investigated, and the interaction between temperature control unit and heat sink were discussed. The results show that the hybrid systems with the newly designed heat transfer pillar and circular fins have higher efficiency. After that, a united structure optimization by artificial neural network-multi-objective genetic algorithm was performed to solve the interaction and to balance the electrical efficiency and power density of hybrid system. The comprehensive power generation performance of hybrid system can be further improved after the optimization. The system with PCM thickness dPCM = 6.33 mm, heat transfer pillar width a = 18.19 mm, fin length L = 49.99 mm and fin radius R = 50 mm, has the maximum average total efficiency (31.83%, 2.98% higher than the typical system); the system with dPCM = 3.02 mm, a = 10.05 mm, L = 47.03 mm and R = 25.86 mm, has the maximum average power density (36.97 W/kg, 15.78% higher than the typical system).

Performance investigation of a concentrated photovoltaic-thermoelectric hybrid system for electricity and cooling production

To fully exploit inlet sunlight, a novel hybrid system comprising a concentrated photovoltaic cell, a thermoelectric generator, and a thermoelectric cooler is established. The thermoelectric generator generates electricity by thermally harnessing the solar spectrum energy unavailable to the concentrated photovoltaic cell and then drives the thermoelectric cooler to produce additional cooling. With full consideration of internal and external irreversibility, the numerical model of the hybrid system is developed, where comprehensive heat transfer equations are constructed by the effectiveness-number of transfer units method. Subsequently, the performance characteristics of the system are evaluated by energetic and exergetic analysis. Over the operating range of the thermoelectric unit, when the performance enhancement of the hybrid system is maximized, the associated power density, energy efficiency, and exergy efficiency are, respectively, 42.828 Wm-2, 0.0251, and 0.0255, which are improved by 3.53%, 3.72%, and 3.66% in comparison to the stand-alone concentrated photovoltaic system. Meanwhile, the exergy destruction rate density is reduced by 0.49%. Furthermore, comprehensive sensitivity analyses are undertaken to derive the effects of critical designing parameters and operating conditions on the overall performance. The obtained outcomes may contribute to the design and operation of such a cogeneration system.

Bending strength evaluation and power generation performance optimization of a curved photovoltaic-thermoelectric hybrid device

Curved photovoltaic-thermoelectric (PV-TE) hybrid devices have great potential applications in the fields of aerospace, navigation and daily life. During the application, the curvature radius of the PV-TE hybrid device needs to be altered to fit different curved surfaces. Naturally, the bending strength of the curved hybrid device is a very important issue. This paper evaluates the bending strength and optimizes the output power and energy conversion efficiency of the curved hybrid device. The stress solutions are obtained by means of the variational principle. The recovery of transverse shear stress is achieved by using the Cauchy’s polar equilibrium equation. It is found that the thermal stress is much smaller than the bending stresses induced by the bending deformation of the hybrid device. The circumferential stress is the key factor that results in the failure of the hybrid device. The optimization of the curvature radius of the hybrid device is conducted and the safety region is identified to protect the hybrid device from strength failure. The ratio of thickness to cross-sectional area of the thermoelectric leg is optimized to obtain the optimum power generation performance of the hybrid device. This paper offers some favorable suggestions for structural design of the curved hybrid device.

Interlaminar mechanical performance of a multi-layered photovoltaic-thermoelectric hybrid device

A concentrated photovoltaic-thermoelectric hybrid device made up of a six-layer composite structure is considered. The hybrid device is composed of, from top to bottom, photovoltaic cell, ethylene vinyl acetate (EVA) layer, tedlar polyester tedlar (TPT) layer, ceramic layer, electrode, and thermoelectric legs. Under the service condition, the poor interlaminar mechanical performance of the hybrid device induced by the high interlaminar stresses level can give rise to very poor power generation performance. To understand this, an analytical model is built to study the influence of the thermal contact resistance and interfacial slip stiffness on the interlaminar stresses of the hybrid device. In particular, effects of the material parameters and geometric dimensions of the hybrid device are also studied by using the state space method. It is found that the thermal contact resistance mainly affects the interlaminar stresses of the photovoltaic module. The interlaminar stresses without considering the temperature-dependent material properties are greater than the actual stresses. The highest interlaminar shearing stress appears at the lower surface of the photovoltaic cell and the maximum peeling stress occurs at the interface between the EVA layer and TPT layer. A lower interfacial slip stiffness is conducive to reducing the interlaminar stresses. The interlaminar stresses decrease with decreasing elastic modulus and coefficient of thermal expansion of the EVA layer. In addition, a thinner thermoelectric layer contributes to lower the interlaminar stresses. The results offer helpful suggestions for the optimization of the interlaminar mechanical performance of the hybrid device.

Maximizing Electric Power through Spectral-Splitting Photovoltaic-Thermoelectric Hybrid System Integrated with Radiative Cooling.

As zero-emission technologies, a daytime radiative cooling (RC) strategy developed recently, and photovoltaic (PV) and thermoelectric (TE) technologies have aroused great interest to reduce fossil fuel consumption and carbon emissions. How to integrate these state-of-the-art technologies to maximise clean electricity from the sun and space remains a huge challenge, and the limit efficiency is still unclear. In this study, a spectral-splitting PV-TE hybrid system integrated with RC is proposed to maximise clean electricity from the sun and space without any emissions. For the sun acting as a typical constant heat-flux heat source, the current thermoelectric theory overestimates the thermoelectric efficiency highly since the theory is based on constant temperature-difference conditions. A new theory based on heat-flux conditions is employed to achieve maximum thermoelectric efficiency. The PV-TE hybrid system with RC is superior to the conventional hybrid system, not only in terms of higher efficiency but also in its 24-h operation capacity. In a system with a single-junction cell, the total efficiency with 30 suns (39.4%) is higher than the theoretical PV efficiency at 500 suns (38.2%). In a hybrid system with four-junction cells, total efficiency is over 65% which is superior to most current photoelectric and thermal power systems.

Parabolic trough photovoltaic thermoelectric hybrid system: Simulation model, parametric analysis, and practical recommendations

Parabolic trough photovoltaic thermoelectric hybrid system: Simulation model, parametric analysis, and practical recommendations

Multi-objective optimization of a concentrated spectrum splitting photovoltaic-thermoelectric hybrid system

This paper presents a comprehensive multi-objective optimization process of the concentrated spectrum splitting photovoltaic-thermoelectric hybrid system, including sensitivity analysis, parameter evaluation, and genetic algorithm. The coupling efficiency and the efficiency difference compared to the concentrated photovoltaic system are simultaneously taken as the optimization objectives. Theoretical models of the two systems are established. The key influencing factors are determined, and their effects on the operating temperatures and efficiencies are investigated. The Pareto front and optimal working conditions are acquired, and the impacts of the thermoelectric figure of merit on the optimization results are further studied. The results demonstrate that the photovoltaic bandgap, splitter cutoff wavelength, concentration ratio, cooling performance, and thermoelectric structure factor are the system's key influencing factors. The two optimization objectives are negatively correlated, attributed to the effect of the PV bandgap. The cost and lifetime need to be further considered to identify the optimal solution. For the current thermoelectric devices, the coupling system achieves the highest coupling efficiency at the photovoltaic bandgap of about 1.42 eV and the maximum system efficiency difference near the photovoltaic bandgap of 1.65 eV.

Output-power equivalence of two- and four-terminal photovoltaic-thermoelectric hybrid tandems

Two- and four-terminal photovoltaic (PV)–thermoelectric (TE) hybrid tandems are studied theoretically based on the scaling of coupled nonlinear equations for heat and electrical currents. We generally prove the equivalence between achievable output powers by two- and four-terminal tandems. If the PV and TE segments are adjusted in terms of numbers, areas, and connections in a four-terminal tandem, lossless matching is always possible in current or voltage for series or parallel two-terminal tandems while maintaining other designs, materials, or installation environments. That is, the same output power is always achievable in two- and four-terminal tandems using such adjustments.

High-efficiency photovoltaic-thermoelectric hybrid energy harvesting system based on functionally multiplexed intelligent thermal management

A photovoltaic-thermoelectric hybrid (PV-TEH) system with intelligent thermal management based on the dual functions of thermoelectrics (TEs) is proposed to improve the conversion efficiency of PV cells. The performance of PV cells is highly dependent on the cell temperature, and the temperature gradient can also be used to generate additional electricity. A microcontroller switching circuit is designed using the same thermoelectric module for the functions of thermoelectric generator and thermoelectric cooler (TEG/TEC) to selectively regulate the PV panel temperature according to the heat dissipation requirements. In addition, PWM-based intelligent cooling regulation technology is presented to set up a hybrid energy harvesting and thermal management system with adjustable conversion efficiency. Experimental results show that the conversion efficiency in the proposed hybrid PV-TEH system can reach up to 27.8 % while reducing the temperature of the PV panel by 6℃. Accounting for 23 % of the high-efficiency energy output due to the PV-TEG mode, the time window of the pure power supply is increased to 1.15 h during the 5 h day measurement. In addition, the effective output power of PV is increased from 6 W to 8.1 W in PV-TEC mode. This intelligent energy harvesting and thermal management by employing the TE functionally multiplexed technique can provide a reference for green self-powered electronic equipment.

Design of high-performance photovoltaic-thermoelectric hybrid systems using multi-objective genetic algorithm

Hybrid systems which integrate photovoltaic (PV) and thermoelectric generator (TEG) can improve the utilization of solar energy. In this study, a multi-objective genetic algorithm (MOGA) is adopted to maximize the output power and conversion efficiency for the PV-TEG system, where the CFD model is coupled in the optimization procedure and the penalty function is employed to ensure the appropriate operating temperature. Meanwhile, two geometric parameters along with two boundary conditions are selected as the design variables, while the effects of three cooling conditions are also discussed. Compared with the PV only system, the output power of the PV-TEG system is improved by up to 11.52% with the conversion efficiency also improved by 44.97%. At the same solar concentration condition, the optimal PV-TEG system could increase the output power by 36%. Based on the analysis of optimal solutions, it is demonstrated that the adopted TEG contributes significantly to the output power, while a better cooling condition also has a positive effect on the comprehensive performances. Furthermore, a multiple-criteria decision-making approach is applied to balance output power and conversion efficiency. Compared with the maximum efficiency solution, the best compromise solution increases output power by 120.02% and decreases the efficiency only by 14.83%.

Efficiency improvement of hybrid PV-TEG system based on an energy, exergy, energy-economic and environmental analysis; experimental, mathematical and numerical approaches

Nowadays, Photovoltaic panels are being used as effective devices to utilize solar free energy. However, they lose their efficiency when their temperature increases; consequently, a large portion of the solar energy is wasted. In this study, a hybrid system of polycrystalline Photovoltaic panel equipped with Thermoelectric generator modules and combined with water-cooled heat exchangers has been proposed to extract more power from the Photovoltaic meanwhile producing electricity by Thermoelectric generators and absorbing heat by water. Previous studies have been mostly based on a 24-hour simulation while not considering the long-term analysis of the system. This study includes a 24-hour analysis via experimental build testing, mathematical modelling, and finite element simulation, followed by a finite element simulation carried out for one year. This study considers the influence of varying irradiance and thermal resistance on the Photovoltaic, Thermoelectric hot and cold sides and outlet water temperatures on the daily and annual energy, exergy, environmental, and energy-economic outcomes. It was found that the averaged maximum Photovoltaic temperature for the experiment and simulations of the Photovoltaic-Thermoelectric hybrid system was 44.2°C at maximum irradiation. In comparison, it was 57.1°C for the stand-alone Photovoltaic. The electrical power production of the Photovoltaic-Thermoelectric hybrid system was 9.49W, which is noticeably higher than the 8.48W output of the stand-alone Photovoltaic meaning that the electrical efficiency and the exergy efficiency increased by 1.67%, and 1.72%, respectively. The environmental and energy-economic simulations show that the carbon payback period and the discounted payback period are 1.31 and 12.39 years, respectively.

Numerical and experimental performance evaluation of a laser-concentrated photovoltaic-thermoelectric generator hybrid system.

Thermal management of concentrated photovoltaic (CPV) modules is essential to avoid the decrease in conversion efficiency caused by temperature rise during their operation. This is even more important for laser-concentrated CPV hybrid systems where out-of-control temperature rise is more likely to happen. In this research, a three-dimensional simulation model for a concentrated photovoltaic-thermoelectric (CPV-TE) hybrid system was studied to optimize its parameters and improve its conversion efficiency under laser radiation. Based on the simulation results, an integrated CPV-TE device was designed, fabricated, and tested under a high-power laser. The novel integrated CPV-TE system utilizes growing electrodes to encapsulate CPV directly on the TEG. Compared to conventional CPV-TE systems that utilize silicone-filled, the integrated CPV-TE system reduces contact thermal resistance and increases output power as well as conversion efficiency. To the best of our knowledge, this is the first study to discuss and optimize a CPV-TE hybrid system for laser radiation. In addition, this research improves the efficiency of laser energy conversion, increases the reliability and stability of the system, and may facilitate the promotion of optical wireless and fiber power transmission systems in future applications.

Achieving extensive lossless coupling of photovoltaic and thermoelectric devices through parallel connection

Photovoltaic-thermoelectric hybrid systems have received broad attention in recent years owing to the capability of achieving efficient utilization of full-spectrum solar energy. This paper investigates the lossless coupling method of photovoltaic and thermoelectric devices to address the issue of large electrical coupling losses. The properties of the photovoltaic-thermoelectric hybrid systems with three connection modes, which are electrically separated, series, and parallel, are experimentally compared under different incident power densities. The electrical-thermal interaction characteristics of the photovoltaic cell and the thermoelectric device under different connection modes are further investigated with the theoretical method. The mechanism of achieving extensive lossless coupling of photovoltaic and thermoelectric devices under parallel connection is illustrated. The results demonstrate that when the incident power density is less than 15Wcm−2, the photovoltaic and thermoelectric devices can be losslessly coupled by the parallel connection. Both electrically separated and parallel coupling systems achieve the output power of 0.85 W, while the series coupling system power is only 0.41 W under the same incident power density of 15Wcm−2. Compared with the series mode, the parallel lossless coupling method can be achieved over a broader range of operating conditions and is more stable because of the small variation of the photovoltaic maximum power voltage under the practical varying irradiation and the effect of the weakened Peltier effect.

Evaluation of parameters influencing the performance of photovoltaic-thermoelectric (PV-TE) hybrid system

Abstract This study analyzes the feasibility of the photovoltaic-thermoelectric (PV-TE) hybrid system and examines the appropriate parameters to optimize the design of the hybrid system. A new formula that sets a minimal working condition from which the output power of the hybrid system will exceed that of the PV cell alone at 298 K was developed. The experimental results showed that the hybrid system outperformed the PV cell alone at 298 K, once the minimal working condition is attained. Moreover, the results illustrated that we can enhance the performance with a slight change in the cold side temperature of the TE using PV cells with a relatively small temperature coefficient and efficiency. The results indicated also that the model can produce trustworthy predictions, consequently, it may be useful during the design of a hybrid system with optimized performance.